Which of the following fabrics is preferred for winter garments?
A) Nylon
B) Cotton
C) Wool
D) Silk

Hint: Just remember, it is not wool that generates heat to keep us warm, it is our body that generates heat. Wool just inhibits the heat of the body to escape to the surroundings. Thus, wool is a good insulator.

Complete step by step solution:
In winter our body needs heat to keep us warm.
As we all know, our body generates heat itself and not the wool. What wool does is, it prevents the heat of the body from escaping.

Woolen fibers trap a large number of air particles in it. As wool and air both are bad conductors of heat, so it prevents the heat from flowing from our body to the surroundings.
Also, wool acts as a barrier between the heat of the body and the surrounding air. As we know, the air at room temperature is cooler than the heat of the human body. The air carries away the heat produced by the human body with itself. Therefore, wearing wool will prevent the air from carrying heat. Also, wool is reflexive in nature as the heat generated by the body reflects the body after striking the wool. That’s why we feel warm. Therefore, wool is preferred as a good fiber for the winters.

Hence, option (C) is the correct option.

Note: Keep in mind, wool consists of a protein called keratin which is also present in animal hair. Keratin is a material which is helical in nature. Due to this helical structure, air can be trapped in the fibers. This entrapped air, preventing the heat from escaping out of the body.